The cooling system which cools a combustion engine in a vehicle is also many times used to cool various mediums of different systems of the vehicle. The coolant of the coolant system can be used to cool the working medium of an AC system in a condenser, charge air in a charge air cooler, recirculating exhaust gases in an exhaust cooler and the working medium of a WHR system in a condenser.
In order to achieve a high thermal efficiency of a WHR-system, the working medium is to be cooled in the condenser by the coolant to a condensation temperature that is as low as possible and substantially without subcooling. Thus, the working medium is to be cooled with a cooling effect of a specific value. However, heating of the working medium in an evaporator of the WHR system varies during different operating conditions and especially when the WHR system absorbs heat energy from the exhaust gases of a combustion engine. The required cooling of the working medium in the condenser varies in a corresponding manner. It is difficult to control a cooling system such that it provides a rapidly adjustable cooling of the working medium in the condenser and especially a rapidly adjustable cooling of the working medium at which a substantially continuous condensation temperature is maintained in the condenser at which the WHR system receives a high thermal efficiency.
US 2013/0118423 shows a cooling circuit with a circulating coolant which cools a motor. The cooling circuit comprises a cooling line where the coolant cools a working medium in a condenser of a WHR-system and a bypass line leading the medium past the condenser. The coolant flow through the bypass line is controlled by a relief valve which opens at a specific pressure.